European Journal of Plant Pathology (2003) 109, 261-267

Piero Roggero, Hervé Lot, Sylvie Souche, Riccardo Lenzi and Robert G. Milne (2003)
Occurrence of Mirafiori lettuce virus and Lettuce big-vein virus in relation to development of big-vein symptoms in lettuce crops
European Journal of Plant Pathology 109 (3), 261-267
Abstract: Big-vein disease (BV) of lettuce has been attributed to infection by Lettuce big-vein virus (LBVV), vectored by the soil fungus Olpidium brassicae. The finding of a second soil-borne virus in lettuce, Mirafiori lettuce virus (MiLV), led to a re-investigation of the role of LBVV in big-vein disease, with evidence emerging that both MiLV and LBVV are vectored by O. brassicae, and that MiLV, not LBVV, is the cause of BV (Lot et al. (2002), Phytopathology 92: 288-293). The two viruses have coat proteins of similar size but have different morphologies and are serologically unrelated. We tested individual lettuce plants in BV-prone fields and protected crops in France and Italy for the presence of the two viruses, using DAS-ELISA and antisera specific for each virus. Both MiLV and LBVV were found at high incidence, often together but sometimes separately. Symptoms were frequently found to be associated with MiLV alone or both viruses, but rarely LBVV alone. However, no absolute correlation emerged, because sometimes MiLV was present in the absence of symptoms, and vice versa. To clarify the situation, individual lettuce plants were examined over a period of time in two further surveys. In surveys of protected crops in France, plants with big-vein were always ELISA-positive for MiLV, or else symptomless plants positive for MiLV were later seen to develop big-vein symptoms. Presence or absence of LBVV appeared to have no effect on symptom development. In surveys of open fields in Italy, all combinations were found: presence of both viruses, apparent absence of both viruses, or presence of each one alone, in plants that developed BV. At the end of the observation period, nearly all plants had BV and contained both viruses.
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Link to article at publishers website
Database assignments for author(s): Piero Roggero

Research topic(s) for pests/diseases/weeds:
surveys/sampling/distribution
population dynamics/ epidemiology

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Varicosavirus lactucae	Lettuce (Lactuca)	France
	Varicosavirus lactucae	Lettuce (Lactuca)	Italy
	Ophiovirus mirafioriense	Lettuce (Lactuca)	France
	Ophiovirus mirafioriense	Lettuce (Lactuca)	Italy